Ontario’s anti-sprawl policies, which some critics have blamed for the current housing supply shortage in Toronto and the surrounding areas, are going to get tougher, with the government demanding that most future development in the province’s south take place in existing neighbourhoods.

Any future projects on undeveloped land will have to accommodate more people and jobs — a minimum of 80 per hectare, up from the current 50 — and there will be higher density targets around GO Transit and subway stations, light rail and bus rapid transit.

The province is giving municipalities until 2031 to meet the new, tougher targets set out in its updated growth plan for the Greater Golden Horseshoe region, which stretches from the Niagara Region to Peterborough, Ont. The new rules will be phased in, with interim targets in 2022.

Municipal Affairs Minister Bill Mauro said Thursday that the objective of the plan is “building complete and more compact communities, that support transit, create jobs, reduce sprawl and protect our environment.”

Under the plan, 60 per cent of new residential development will take place in already developed areas, up from 40 per cent today.

The growth plan is mean to accommodate the growing population in the Greater Golden Horseshoe, which is expected to reach 13.5 million by 2041, an increase of 4 million people.

The province’s growth plan has been facing some criticism, especially from building industry groups that argue it prevents them from building more detached homes and townhomes that would ease some of the pressure on the housing market in the Greater Toronto and Hamilton Area.

But proponents of the plan say it protects agricultural and ecologically sensitive land and creates walkable communities that can be well-served by transit.

Oakville, Ont., Mayor Rob Burton welcomed the plan, saying the kind of dense development the growth plan supports can be maintained with lower tax rates than urban sprawl.

“The mayors have been lobbying for these changes for more than two years, and it’s a very good day for our residents,” said Burton.

The update also adds urban river valleys and coastal wetlands to the Greenbelt — an 800,000-hectare area of farmland, green space and wetlands around the Greater Toronto and Hamilton Area that is protected from development. The changes also establish stronger protections of water systems, and loosen some of its rules concerning the uses of farmland.

The province was expected to bring in new rules following recommendations from an expert panel that studied the government’s four land-use plans — the Growth Plan for the Greater Golden Horseshoe, the Niagara Escarpment Plan, the Greenbelt Plan and the Oak Ridges Moraine Conservation plan — for two years. The panel recommended updates to each of the plans. The updates to the Niagara Escarpment Plan will come into force on June 1, and the other three plans on July 1.

Former Toronto mayor David Crombie, who chaired the expert panel, said political leaders should empower a secretariat within government to make sure the land-use plans are followed on the ground, noting there was little data collected on prior implementation of the growth plan.

“We need to measure and monitor how well we’re doing over the next number of years to know how well we’re going to do and fix it as we go,” Crombie said.